Multilayered wiring board and method for fabricating the same

ABSTRACT

In a multilayered wiring board constituted by laminating to form pluralities of layers of wiring layers  105, 108, 110  and insulating layers  104, 106, 107 , in the plurality of laminated insulating layers  104, 106, 107 , the insulating layer  106  disposed at a laminating center in a laminating direction is made to constitute an insulating layer with a reinforcing member including a reinforcing member.

This is a continuation application of prior application Ser. No.11/509,723, filed on Aug. 25, 2006, now U.S. Pat. No. 8,222,527, whichis incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a multilayered wiring board and amethod for fabricating the same, particularly relates to a multilayeredwiring board provided with reinforcing means for preventing warp and amethod for fabricating the same.

Currently, high function formation and small-sized formation of anelectronic apparatus using a semiconductor device of a semiconductorchip or the like has been progressed, also a semiconductor device isconstituted by high density formation in accordance therewith, andmultipins formation and small-sized formation thereof have beenachieved. As a board mountable with a semiconductor device constitutedby multipins formation and small-sized formation in this way, amultilayered wiring board utilizing a build-up method is provided.

A multilayered wiring board of this kind is constructed by aconstitution constituting a core layer by a reinforcing member of aglass cloth copper plated laminated plate or the like and formed with aninsulating layer and a wiring layer alternately at both faces thereof.The multilayered wiring board of the constitution can be mounted with asemiconductor device constituted by high density formation since awiring layer thereof can be formed to be miniaturized.

However, since the multilayered wiring board includes the core layer atinside thereof, it is difficult to miniaturize a penetrated through holeformed at the core layer to pose a problem that high density of a totalof the multilayered wiring board cannot be achieved. Further, there isalso posed a problem that by providing the core layer, the multilayeredwiring board becomes necessarily thick to hamper the small-sizedformation of an electronic apparatus. Therefore, in recent years, adevelopment of a multilayered wiring board which is not provided with acore layer has been carried out in the multilayered wiring boardutilizing the build-up method (refer to Patent Reference 1).

FIG. 1 shows an example of using a multilayered wiring board 10 which isnot provided with a conventional core layer as a semiconductor package.The example shown in the drawing is constructed by a constitution ofmounting a semiconductor element 13 at an upper portion of themultilayered wiring board 10 and arranging a solder ball 14 at a lowerportion thereof. As shown by the drawing, by not forming the core layer,thin-sized formation of the multilayered wiring board 10 can beachieved.

[Patent Reference 1]

Pamphlet of International Patent Publication No. WO2003/039219

However, there poses a problem that by simply removing the core layerfunctioning as a reinforcing member, warp is brought about at themultilayered wiring board owing to a difference of thermal expansion ofthe insulating layer made of resin and the wiring layer made of metal.When the warp is brought about, a semiconductor device or the likecannot properly be mounted to the multilayered wiring board in amounting step to deteriorate mounting reliability. Further, there is aconcern that interlayer connection of the wiring layer cannot firmly becarried out at inside of the multilayered wiring board and alsoreliability of the multilayered wiring board is deteriorated.

Therefore, as shown in FIG. 1, there is proposed also a constitution ofarranging a reinforcing plate 11 formed with an opening portion 12 at anarea of mounting the semiconductor element 13 of the multilayered wiringboard 10 and reinforcing the multilayered wiring board 10 by thereinforcing plate 11. However, according to the multilayered wiringboard 10 of the constitution, not only a number of parts is increasedbut also the multilayered wiring board 10 becomes thick by an amount ofa thickness of the reinforcing plate 11.

The invention has been carried out in view of the above-described pointand it is an object thereof to provide a multilayered wiring boardcapable of restraining warp from being brought about while achievingthin-sized formation.

In order to resolve the above-described problem, according to theinvention, there is provided a multilayered wiring board including:wiring layers; and insulating layers, wherein the wiring layers and theinsulating layers are laminated to form plurality of layers, and some ofthe plurality of laminated insulating layers are insulating layersincluding reinforcing members.

According to the invention, warp can be restrained from being broughtabout at the multilayered wiring board since the multilayered wiringboard is interposed with the insulating layer including reinforcingmember increasing a strength thereof by the reinforcing member.

Further, the insulating layer with the reinforcing member is constructedby a constitution of mixing the reinforcing member to a material thesame as a material of other insulating layer and therefore, theinsulating layer including reinforcing member can be formed and workedequivalently to other insulating layer. Therefore, warp can berestrained from being brought about while achieving thin-sized formationof the multilayered wiring board by making portions of the insulatinglayers constituting the multilayered wiring board function as thereinforcing members without separately providing the reinforcingmembers.

Further, in the invention, the insulating layer including reinforcingmember may be a woven cloth or a nonwoven cloth impregnated by a resin.

Further, in the invention, the insulating layer may be formed by aresin.

Further, in the invention, the insulating layer including reinforcingmembers may be the resin mixed with reinforcing member.

Further, in the invention, if the plurality of laminated insulatinglayers are the laminated insulating layers including reinforcingmembers, an effect of restraining occurrence of warp is furtherincreased.

Further, in order to resolve the above-described problem, according tothe invention, there is provided a method of fabricating a multilayeredwiring board including the steps of: repeatedly forming a wiring and aninsulating layer by using a resin on a support board, and removing thesupport board, wherein in the steps of forming the insulating layers, atsteps of forming portions of the insulating layers, the insulatinglayers are formed by a resin including a reinforcing member.

According to the invention, at the step of forming portions of theinsulating layers, by simply changing the material of the insulatinglayer to the resin including the reinforcing member, the insulatinglayer functioning as the reinforcing member can be formed at alaminating center. In this way, only the material (resin) may be changedwithout changing the laminating step and therefore, even when the resinlayer including the reinforcing member is formed at the laminatingcenter, fabricating steps are not complicated.

Further, in the invention, the insulating layer may be made by build-upresin.

Further, if the invention further includes the steps of: pastingtogether two sheets of the support boards; and separating the two sheetsof the support boards respectively formed with the insulating layers andthe wirings, an efficiency of fabricating the multilayered wiring boardis improved.

Further, if the invention further includes the steps of: respectivelypasting two sheets of the support boards to a first face and a secondface of a holding board holding the two sheets of the support boards;and separating the two sheets of the support boards respectively formedwith the insulating layers and the wirings from the holding board, theefficiency of fabricating the multilayered wiring board is improved.

Further, the invention may further include the step of: mounting asemiconductor chip to the multilayered wiring board.

Further, in the invention, the step of removing the support board may becarried out after the step of mounting the semiconductor chip.

According to the invention, warp can be restrained from being broughtabout while achieving a thin-sized formation of the multilayered wiringboard.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a multilayered wiring boardaccording to a conventional example.

FIG. 2 is a sectional view showing a multilayered wiring board accordingto an embodiment of the invention.

FIGS. 3A to 3E illustrate views for explaining a method of fabricating amultilayered wiring board according to an embodiment of the invention inline with a fabricating procedure.

FIG. 4 is a diagram showing a relationship between a total thickness anda warp amount of a multilayered wiring board.

FIGS. 5A to 5C illustrate views showing multilayer structures ofrespective multilayered wiring boards shown in FIG. 4.

FIGS. 6A to 6E illustrate views showing various modified examples of amultilayer structure of a multilayered wiring board.

FIGS. 7A and 7B illustrate views showing a modified example of afabricating method of FIG. 3 (part 1).

FIG. 8 is a view showing the modified example of the fabricating methodof FIG. 3 (part 2).

FIG. 9 is a view showing the modified example of the fabricating methodof FIG. 3 (part 3).

FIGS. 10A and 10B illustrate views showing other modified example of thefabricating method of FIG. 3 (part 1).

FIG. 11 is a view showing other modified example of the fabricatingmethod of FIG. 3 (part 2).

FIG. 12 is a view showing other modified example of the fabricatingmethod of FIG. 3 (part 3).

FIGS. 13A and 13B illustrate views showing a method of mounting asemiconductor chip to the multilayered wiring board of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Next, the best mode for carrying out the invention will be explained inreference to the drawings.

FIG. 2 shows a multilayered wiring board 100 according to an embodimentof the invention. Further, as shown by the drawing, according to theembodiment, an explanation will be given by taking an example of a 4layers laminated structure as the multilayered wiring board 100.However, application of the invention is not limited to the 4 layerslaminated structure but is widely applicable to a multilayered wiringboard having various numbers of layers.

The multilayered wiring board 100 is constructed by a constitution ofsuccessively laminating a first insulating layer 104, a wiring 105, asecond insulating layer 106, a wiring 108, a third insulating layer 107,and a wiring 110 from a lower layer to an upper layer as a grossclassification. A lower face of the first insulating layer 104 is formedwith a solder resist 102 and an upper face of the third insulating layer107 is formed with a solder resist 109.

The first insulating layer 104 and the third insulating layer 107 aremade of, for example, a build-up resin of epoxy species having athermosetting property. Further, the build-up resin is not limited tothat having the thermosetting property but a build-up resin havingphotosensitivity or other insulating resin can also be used.

Further, the second insulating layer 106 is constructed by aconstitution having mechanical strength (rigidity, hardness or the like)higher than those of the insulating layers 104, 107 by putting areinforcing member to the build-up resin of epoxy species having thethermosetting property similar to those of the respective insulatinglayers 104, 107. Specifically, the second insulating layer 106 isconstituted by an insulating layer including a reinforcing memberimpregnating the build-up resin to woven cloth or nonwoven cloth ofglass, aramid, LCP (Liquid Crystal Polymer) fiber. According to theinvention, the second insulating layer 106 promoting the mechanicalstrength is characterized in being arranged at a center position in alaminating direction (laminating center position). Further, detailsthereof will be described later for convenience of explanation.

On the other hand, the wiring board 100 is formed by laminating thewirings 105, 108, 110 along with the respective insulating layers 104,106, 107. The respective wirings 105, 108, 110 are formed by, forexample, Cu.

The wiring portion 105 is constituted by a via plug portion 105 a and apattern wiring portion 105 b. The via plug portion 105 a is formed at anopening portion formed at the first insulating layer 104, and an upperface of the first insulating layer 104 in the drawing is formed with thepattern wiring portion 105 b.

An upper end of the via plug portion 105 a in the drawing is connectedto the pattern wiring portion 105 b, and a lower end portion thereof isconnected to an electrode 103. The electrode 103 is formed at an openingportion of the solder resist 102 formed at a lower face of the firstinsulating layer 104. The electrode 103 functions as an externalconnection terminal and is arranged with a solder ball or the like asnecessary (which is not provided in the embodiment).

The wiring 108 is constituted by a via plug portion 108 a and a patternwiring portion 108 b. The via plug portion 108 a is formed at an openingportion formed at the second insulating layer 106, and an upper face ofthe second insulating layer 106 in the drawing is formed with thepattern wiring portion 108 b. An upper end of the via plug portion 108 ain the drawing is connected to the pattern wiring portion 108 b, and alower end portion thereof is connected to the pattern wiring portion 105b of the wiring 105.

The wiring 110 is constituted by a via plug portion 110 a and anelectrode portion 110 b. The via plug portion 110 a is formed at anopening portion formed at the third insulating layer 107, and an upperface of the third insulating layer 107 in the drawing is formed with theelectrode portion 110 b. A position of the electrode portion 110 b isset to an opening portion 109A of the solder resist 109 formed at anupper face of the third insulating layer 107. Therefore, the electrodeportion 110 b is constructed by a constitution of being exposed from thesolder resist 109 by way of the opening portion 109A. The electrodeportion 110 b functions as an external connection terminal. Theelectrode portion 110 b is connected with, for example, a semiconductorelement or the like (which is not provided in the embodiment).

The multilayered wiring board 100 constructed by the above-describedconstitution is provided with the second insulating layer 106(insulating layer including reinforcing member) constructed by aconstitution having the mechanical strength (rigidity, hardness or thelike) higher than those of the insulating layers 104, 107 by includingthe reinforcing member. Further, the second insulating layer 106 isprovided to be disposed at a laminating center of the multilayeredwiring board 100 laminated to be formed.

Thereby, the third insulating layer 107 and the wiring 110 arrangedabove the second insulating layer 106 and the first insulating layer 104and the wiring 105 arranged therebelow are symmetrically arrangedcentering on the second insulating layer 106. Thereby, a balance in anup and down direction constituting the center by the second insulatinglayer 106 of the multilayered wiring board 100 is improved, and warp canbe restrained from being brought about at the multilayered wiring board100.

Further, the second insulating layer 106 is constructed by aconstitution of constituting a base by a material the same as a materialof the other insulating layers 104, 107 and mixing the reinforcingmember thereto. Therefore, the second insulating layer 106 can be formedand worked equivalently to the other insulating layers 104, 107.Therefore, it is not necessary to separately provide the reinforcingmember (refer to FIG. 1) as in the background art, and by making thesecond insulating layer 106 constituting one layer constituting themultilayered wiring board 100 function as the reinforcing member, warpcan be restrained from being brought about while achieving thin-sizedformation of the multilayered wiring board 100. Further, themultilayered wiring board 100 can be formed by following the build-upmethod and therefore, thin-sized formation of the multilayered wiringboard 100 can be achieved.

Successively, an explanation will be given of a method of fabricatingthe multilayered wiring board 100 constructed by the above-describedconstitution in reference to FIG. 3 as follows. Further, constitutionsin FIG. 3 in correspondence with constitutions shown in FIG. 2 areattached with the same notations.

In fabricating the multilayered wiring board 100, first, a support board101 shown in FIG. 3A is prepared. The support board 101 is made of aconductive material of, for example, Cu or the like. The solder resistlayer 102 made of a photosensitive resin material is formed on thesupport board 101. In this case, the solder resist layer 102 can beformed by a method of, for example, laminating or coating aphotosensitive resin film or the like.

Next, the solder resist layer 102 is patterned by irradiatingultraviolet ray thereto by way of a mask pattern (not illustrated) andexposing the solder resist layer 102 to form an opening portion 102A.There is brought about a state of exposing the support board 101 fromthe opening portion 102A. Further, the solder resist layer 102 may beformed by printing a thermosetting resin material of epoxy or the liketo provide the opening portion 102A by a screen printing method.

Next, electrolytic plating constituting a conductive path by the supportboard 101 is carried out to form the electrode 103 made of, for example,Au/Ni (a plated film laminated with an Au layer, Ni layer in this orderabove the support board 101) at inside of the opening portion 102Aformed at the solder resist 102. FIG. 3B shows a state of forming theelectrode 103 at inside of the opening portion 102A.

Next, at steps shown in FIG. 3C, the first insulating layer 104 and thewiring 105 are formed. First, the first insulating layer 104 (build-uplayer) is formed by coating epoxy resin or the like having athermosetting property, or laminating a resin film on the solder resistlayer 102 and the electrode 103. Next, the first insulating layer 104 isformed with a via hole (opening portion) by using, for example, laser.

Next, the wiring 105 is formed at the first insulating layer 104 byusing a plating method. That is, the via plug portion 105 a is formed atthe via hole of the first insulating layer 104, and the pattern wiringportion 105 b connected to the via plug portion 105 a is formed on thefirst insulating layer 104.

Specifically, a seed layer is formed on the first insulating layer 104by electroless plating, and thereafter, a resist pattern (notillustrated) is formed above the first insulating layer 104 by way ofthe seed layer by a photolithography method. Next, electricity is fedfrom the seed layer by constituting a mask by the resist pattern, Cu isprecipitated by electrolytic plating, thereafter, the resist pattern andthe unnecessary seed layer are removed. Thereby, the wiring 105including the via plug portion 105 a and the pattern wiring portion 105b is formed.

Next, at steps shown in FIG. 3D, there is carried out a processing offorming the second insulating layer 106 on the first insulating layer104. In order to form the second insulating layer 106, first, a filmimpregnated with resin is formed at the reinforcing member constitutinga base member. Successively, the film is laminated on the firstinsulating layer 104.

Specifically, by impregnating resin having a thermosetting property ofepoxy resin or the like to glass cloth, aramid nonwoven cloth, LCP wovencloth or the like, a resin film including the reinforcing member isfabricated and laminated. The resin including the reinforcing member isarranged on the first insulating layer 104 and the pattern wiringportion 105 b. Next, an opening portion 106A (via hole) is formed at thesecond insulating layer 106 by using, for example, laser.

Further, in place of the method, the reinforcing layer including thereinforcing member may be formed by making respective resin layers ofepoxy resin or the like include a filler of silica or the like. In thiscase, the insulating layer is formed by coating the resin including thefiller or laminating the resin film.

Next, at step shown in FIG. 3E, the wiring 108 is formed at the secondinsulating layer 106 by using a plating method, and the third insulatinglayer 107 and the wiring 110 are formed on the second insulating layer106 formed with the wiring 108.

First, in order to form the wiring 108 at the second insulating layer106, the via plug portion 108 a is formed at the opening portion 106A ofthe second insulating layer 106, and the pattern wiring portion 108 b isformed on the second insulating layer 106.

Specifically, a seed layer is formed on the second insulating layer 106by electroless plating, thereafter, a resist pattern (not illustrated)is formed on the second insulating layer 106 by way of the seed layer bya photolithography method. Next, electricity is fed from the seed layerby constituting a mask by the resist pattern, Cu is precipitated byelectrolytic plating, thereafter, the resist pattern and unnecessaryseed layer are removed. Thereby, the wiring 108 including the via plugportion 108 a and the pattern wiring portion 108 b is formed.

Successively, the third insulating layer 107 and the wiring 110 areformed. First, the third insulating layer 107 (build-up layer) made ofepoxy resin or the like having a thermosetting property is formed on thesecond insulating layer 106 and on the wiring 108. Next, a via hole(opening portion) is formed at the third insulating layer 107 by using,for example, laser.

Next, a seed layer is formed on the third insulating layer 107 byelectroless plating, thereafter, a resist pattern (not illustrated) isformed on the third insulating layer 107 by way of the seed layer by aphotolithography method. Further, electricity is fed from the seed layerby constituting a mask by the resist pattern, Cu is precipitated byelectrolytic plating, thereafter, the resist pattern and the unnecessaryseed layer are removed. Thereby, the wiring including the via plugportion 110 a and the electrode portion 110 b is formed.

Next, the solder resist 109 is formed on the third insulating layer 107by a method of laminating or coating a photosensitive resin film. Next,the solder resist 109 is patterned by irradiating ultraviolet raythereto by way of a mask pattern (not illustrated) and exposing thesolder resist 109 to form the opening portion 109A. A position offorming the opening portion 109A is selected to a position of beingopposed to the electrode portion 110 b, thereby, there is brought abouta state of exposing the electrode portion 110 b from the opening portion109A as described above. Further, the solder resist 109 having theopening portion 109A may be formed by printing a thermosetting resinmaterial of epoxy or the like by a screen printing method.

Next, the support board 101 is removed by etching (for example, wetetching) from a state shown in FIG. 3E. The etching processing iscarried out by using an etching solution which dissolves only thesupport board 101 and does not dissolve the electrode 103. At thisoccasion, the etching is carried out by closing the opening portion 109Aby a resist or the like and therefore, the electrode portion 110 b isnot destructed by the etching.

Further, when a semiconductor element is mounted to the multilayeredwiring board 100, there may be constructed a constitution of mountingthe semiconductor element at the electrode portion 110 b previouslybefore removing the support board 101 and removing the support board 101thereafter.

By carrying out the above-described series of steps, the multilayeredwiring board 100 shown in FIG. 2 is fabricated. In the method offabricating the multilayered wiring board 100 according to theembodiment, in forming the second insulating layer 106, by simplychanging a used resin material to a resin including the reinforcingmember, the second insulating layer 106 can be formed.

Further, according to the fabricating method of the embodiment, when thefirst insulating layer 104 and the wiring 105 are formed, the firstinsulating layer 104 and the wiring 105 are supported by the supportboard 101 and therefore, warp is not brought about. Further, afterforming the first insulating layer 104 and the wiring 105, the secondinsulating layer 106 having the high mechanical strength is laminated tobe formed, and the third insulating layer 107 and the wiring 110 aresupported on the second insulating layer 106 having the high mechanicalstrength. Therefore, the third insulating layer 107 and the wiring 110are supported by the second insulating layer 106 and therefore, also informing the third insulating layer 107 and the wiring 110, warp is notbrought about. Therefore, according to the fabricating method accordingto the embodiment, warp can be prevented from being brought about at themultilayered wiring board 100.

Further, also in arranging the insulating layer including thereinforcing member (second insulating layer 106 in the case of theembodiment) made of the resin including the reinforcing member at thelaminating center, when a number of laminating of the multilayeredwiring board 100 is previously determined, the laminating center caneasily be determined. Therefore, the insulating layer including thereinforcing member can easily be disposed at the laminating center.

Further, the multilayered wiring board 100 constituted by thin-sizedformation without warp can be fabricated by simply changing the material(resin) without significantly changing the steps of fabricating themultilayered wiring board which has been carried out in the prior artand therefore, a reduction in equipment cost can also be achieved.Further, in accordance therewith, a reduction in cost of themultilayered wiring board 100 can also be achieved.

Further, according to the method of fabricating the multilayered wiringboard 100 according to the embodiment, a so-to-speak coreless structureis realized by removing the support board 101. Therefore, thin-sizedformation of the multilayered wiring board 100 can be realized.

An explanation will be given here of warp brought about at themultilayered wiring board 100 according to the embodiment in comparisonwith the prior art in reference to FIGS. 4 and 5.

FIG. 4 shows a warp amount at the ordinate and shows a total thicknessof a multilayered wiring board at the abscissa. What is shown in FIG. 4by an arrow mark A is a property of the multilayered wiring board 100according to the embodiment. That is, according to the multilayeredwiring board, as schematically shown in FIG. 5A, the second insulatinglayer 106 (layer having high mechanical strength) is disposed at thelaminating center by being arranged between the first insulating layer104 and the third insulating layer 107.

In contrast thereto, what is shown in FIG. 4 by an arrow mark B shows aproperty when all of the insulating layers 104, 111, 107 are constitutedby the same layers (layers which are not provided with the mechanicalstrength) as schematically shown in FIG. 5B. Further, what is shown byan arrow mark C in FIG. 4 shows a property when the insulating layer 106having the mechanical strength is arranged to be deviated from thelaminating center as is schematically shown in FIG. 5C.

In a case in which the reinforcing member is not used in all of thelayers as shown by the arrow mark B, there is shown a property in whichthe thicker the total thickness of the multilayered wiring board, thesmaller the warp. In contrast thereto, in a case in which the layerincluding the reinforcing member is deviated from the laminating centeras shown by the arrow mark C, it is known that large warp is broughtabout even when the total thickness of the multilayered wiring board isthick.

In contrast thereto, when the layer including the reinforcing member isarranged at the laminating center as in the embodiment, even when thetotal thickness of the multilayered wiring board is thin, occurrence ofwarp is restrained to be small since the balance centering on the secondinsulating layer 106 is excellent. Therefore, it is verified from FIG. 4that according to the multilayered wiring board 100 according to theembodiment, occurrence of warp can be restrained while achieving athin-sized formation.

Further, the thickness of the second insulating layer 106 becomesthicker than those of the other insulating layers 104, 107 since thesecond insulating layer 106 is mixed with the reinforcing member.However, when the thickness is made to be thick more than necessary, thethin-sized formation constituting the problem cannot be achieved. Warpcan be reduced when the thickness of the insulating layer 106 used inFIG. 5A is 100 μm and therefore, it is preferable that the thickness ofthe insulating layer 106 is equal to or smaller than about 100 μm(specifically, about 15 through 100 μm). Further, it is preferable thatthe thicknesses of the normal insulating layers 104, 107 are about 15through 35 μm.

Meanwhile, FIG. 6 shows various modified examples of a multilayerstructure of a multilayered wiring board. Multilayered wiring boardsshown in FIGS. 6A to 6E are provided with a structure of laminating 7layers of insulating layers and constructed by a constitution ofinterposing insulating layers 116 including reinforcing members atportions or a total thereof. Further, in the following explanation, thelayers are designated as first layer, a second layer, . . . a seventhlayer from a lower layer.

According to the multilayered wiring board shown in FIG. 6A, the thirdlayer through the fifth layer disposed at a center are constituted bythe insulating layers 116 including the reinforcing members. Further,the multilayered wiring board shown in FIG. 6B is constructed by aconstitution of constituting the first layer and the seventh layer bythe insulating layers 116 including the reinforcing members and thesecond layer through the sixth layer disposed therebetween areconstituted by normal insulating layers 115.

Further, a multilayered wiring board shown in FIG. 6C is constructed bya constitution of constituting the second layer and the sixth layer bythe insulating layers 116 including the reinforcing members andconstituting the other layers by the normal insulating layers 115.Further, according to the multilayered wiring board shown in FIG. 6D,the first layer and the seventh layer disposed at a top and a bottomthereof are constituted by the insulating layers 116 including thereinforcing members and the center fourth layer is constituted by theinsulating layer 116 including the reinforcing member.

Also in the respective multilayered wiring boards shown in FIGS. 6A to6D, the respective layers laminated by 7 layers are balanced andoccurrence of warp can be restrained. Particularly, constitutions ofproviding the insulating layer 116 including the reinforcing member atthe laminating center of the multilayered wiring boards as shown inFIGS. 6A, 6D, or providing the insulating layers 116 including thereinforcing members at both upper and lower faces of the multilayeredwiring boards as shown in FIGS. 6B, 6D are preferable in view ofpreventing occurrence of warp.

Further, as shown in FIG. 6E, there may be constructed a constitution inwhich all of the laminated insulating layers of the first layer throughthe seventh layer are constituted by the insulating layers 116 includingthe reinforcing members. In this case, an effect of restraining warp ofthe multilayered wiring board is further increased. For example, whenthere is a concern of increasing warp of the multilayered wiring boardin consideration of a stress of a material or the like used in themultilayered wiring board, a number of laminated layers, thicknesses oflayers and the like, as shown in FIG. 6E, it is preferable to constituteall of the laminated insulating layers by the insulating layersincluding the reinforcing members.

Further, although in the above-described explanation of the embodiment,an explanation has been given such that a side of the third insulatinglayer 107 of the multilayered wiring board 100 is made to constitute aface of mounting the semiconductor element, and a side of the firstinsulating layer 104 is made to constitute a face of being arranged withexternal connection terminal, there may be constructed a constitution inwhich the side of the first insulating layer 104 is made to constitutethe face of mounting the semiconductor element, and the side of thethird insulating layer 107 is made to constitute the face of beingarranged with the external connection terminal.

Further, although according to the method of fabricating themultilayered wiring board 100, an explanation has been given byillustrating a procedure of fabricating one piece of the multilayeredwiring board 100 from one piece of the support board 101, actually, aso-to-speak multimember piece taking is carried out. That is, byintegrally forming a number of the multilayered wiring boards 100 on oneof the support board 101, and cutting and segmenting the number ofmultilayered wiring boards 100, the individual multilayered wiringboards 100 are formed. Thereby, a fabrication efficiency can bepromoted.

Further, although according to the embodiment, a method of fabricatingthe multilayered wiring board 100 by using one sheet of the supportboard 101 is shown, as disclosed in, for example, Patent Reference 1,the multilayered wiring board may be formed by using two sheets of thesupport boards and constituting the support boards by a compound boardlaminated with two sheets of the support boards. Further, there may beconstructed a constitution of constituting an electrode portion by abump structure as disclosed in Patent Reference 1.

Further, the fabricating method of fabricating the multilayered wiringboard 100 is not limited to the method shown in FIG. 3 (hereinafter,fabricating method 1) but the multilayered wiring board 100 can befabricated by, for example, various methods shown below.

FIGS. 7A, 7B, 8 and 9 show a fabricating method 2 constituting amodified example of the fabricating method 1 by following a procedurethereof. However, portions explained above are attached with the samenotations and an explanation thereof will be omitted. Further, portionswhich are not particularly explained are made to be similar to those ofthe fabricating method 1.

First, at a step shown in FIG. 7A, two sheets of the support boards 101are pasted together by using an adhering layer 101A made of, forexample, a resin material.

Next, at a step shown in FIG. 7B, a step in correspondence with FIG. 3Bof the fabricating method 1 is carried out to form the solder resistlayers 102 having the opening portion 102A and the electrodes 103respectively at two sheets of the support boards 101 pasted together.

Next, at a step shown in FIG. 8, steps in correspondence with FIGS. 3Cto 3E of the fabricating method 1 are carried out, and the multilayeredwiring boards are respectively formed at two sheets of the supportboards 101. As a result, as shown in FIG. 8, there is formed a structurein which the multilayered wiring boards are respectively formed at twosheets of the support boards 101 pasted together.

Next, in the step shown in FIG. 9, two sheets of the support boards 101pasted together are separated. Thereafter, by respectively removing twosheets of the support boards 101, the multilayered wiring boards 100shown in FIG. 2 can be fabricated.

In the fabricating method 2, the multilayered wiring boards are formedat two sheets of the support boards and therefore, an efficiency offabricating the multilayered wiring board is improved. Further, anamount of warp in the steps of forming the multilayered wiring board isrestrained and the multilayered wiring board can be fabricated byexcellent working accuracy.

Further, FIGS. 10A, 10B, 11 and 12 show a fabricating method 3constituting other modified example of the fabricating method 1 byfollowing a procedure thereof. However, portions explained above areattached with the same notations and an explanation thereof will beomitted. Further, portions which are not explained particularly are madeto be similar to those of the fabricating method 1.

First, at the step shown in FIG. 10A, two sheets of the support boards101 are pasted to both faces of a holding board 101B. The holding board101B is made of, for example, a resin material and holds two sheets ofthe support boards 101 by being pasted with the support boards 101B madeof metal foils of copper or the like at both faces thereof.

Further, although the support board 101 is pasted to the holding board101B by, for example, an adhering agent, in the drawing, illustration ofthe adhering agent is omitted. For example, the adhering agent is usedat a peripheral edge portion of the support board (holding board), andthe support board can be separated from the holding board by removingthe peripheral edge portion using the adhering agent by dicing at laterstep.

Further, at a step shown in FIG. 10B, a step in correspondence with FIG.3B of the fabricating method 1 is carried out and the solder resistlayers 102 having the opening portions 102A and the electrodes 103 arerespectively formed at two sheets of the support boards 101 pasted tothe holding board 101B.

Next, at a step shown in FIG. 11, steps in correspondence with FIGS. 3Cto 3E of the fabricating method 1 are carried out, and the multilayeredwiring boards are respectively formed at two sheets of the supportboards 101. As a result, as shown in FIG. 11, there is formed astructure constituted by forming the multilayered wiring boardsrespectively at two sheets of the support boards 101 pasted to theholding board 101B.

Next, at a step shown in FIG. 12, two sheets of the support boards 101pasted to the holding board 101B are respectively exfoliated. In thiscase, as explained above, the support board 101 can be exfoliated fromthe holding board 101B by, for example, deleting the peripheral edgeportions of the holding board 101B and the support board 101 adhered bythe adhering agent by dicing.

Thereafter, by respectively removing two sheets of the support boards101, the multilayered wiring boards 100 shown in FIG. 2 can befabricated.

According to the fabricating method 3, similar to the case of thefabricating method 2, the multilayered wiring boards are formed at twosheets of the support boards and therefore, the efficiency offabricating the multilayered wiring board is improved. Further, theamount of warp in steps of forming the multilayered wiring board isrestrained and the multilayered wiring board can be fabricated withexcellent working accuracy.

Further, the multilayered wiring board 100 shown in FIG. 2 is mountedwith the semiconductor chip to be connected to the electrode portion110B. In this case, the semiconductor chip may be mounted beforeremoving the support board 101.

FIGS. 13A and 13B are views showing an example of a method of mountingthe semiconductor chip to the multilayered wiring board 100. However,there is a case in which the portions explained above are attached withthe same notations and an explanation thereof will be omitted.

At a step shown in FIG. 13A, a semiconductor chip 201 is mounted to anelectrode portion 110B by a flip chip by using a solder connectingportion (solder ball) 202 before removing the support board 101 from astate shown in any of, for example, FIG. 3E, 9 or 12. Further, anunderfil resin 203 is infiltrated to be cured between the semiconductorchip 201 and the solder resist 109.

Next, at the step shown in FIG. 13B, the support board 101 is removed byetching (for example, west etching). In this way, the multilayeredwiring board mounted with the semiconductor chip can be fabricated.

According to the above-described method, the semiconductor chip ismounted in a state of supporting the multilayered wiring board by thesupport board and therefore, the semiconductor chip is mounted in astate in which flatness of the multilayered wiring board is excellent.Therefore, an effect of improving reliability of mounting thesemiconductor chip is achieved. Further, the semiconductor chip may bemounted after removing the support board.

Further, a number of layers of the multilayered wiring board or leadingwirings, or a mode of mounting the semiconductor chip (for example, flipchip mounting, mounting by wire bonding, or a combination of these) canvariously be modified or changed.

Although the invention has been explained with regard to the preferableembodiments as mentioned above, the invention is not limited to thespecific embodiments but can variously be modified or changed within thegist described in the scope of claims.

What is claimed is:
 1. A wiring board comprising: a reinforcedinsulating layer containing (i) a reinforcing material including a wovencloth or a non-woven cloth and (ii) a resin material therein, thereinforcing material being impregnated by the resin material, thereinforced insulating layer comprising a first surface and a secondsurface opposite to the first surface; a first multilayer wiringstructure disposed on the first surface of the reinforced insulatinglayer and comprising a first inner surface facing the first surface ofthe reinforced insulating layer and a first outer surface opposite tothe first inner surface, the first multilayer wiring structurecomprising: a plurality of first insulating layers each containing amaterial that consists of the same resin material as the reinforcedinsulating layer and does not include the reinforcing material; and aplurality of first wiring layers, a second multilayer wiring structuredisposed on the second surface of the reinforced insulating layer andcomprising a second inner surface facing the second surface of thereinforced insulating layer and a second outer surface opposite to thesecond inner surface, the second multilayer wiring structure comprising:a plurality of second insulating layers each containing a material thatconsists of the same resin material as the reinforced insulating layerand does not include the reinforcing material; and a plurality of secondwiring layers, wherein a first electrode pad is disposed on the firstouter surface of the first multilayer wiring structure, a secondelectrode pad is disposed on the second outer surface of the secondmultilayer wiring structure, a thickness of the reinforced insulatinglayer is 100 μm or less, and a thickness of each of the first and secondinsulating layers is 15-35 μm.
 2. The wiring board of claim 1, furthercomprising: a solder resist layer disposed on the second outer surfaceof the second multilayer wiring structure such that the second electrodepad is exposed from the solder resist layer.
 3. The wiring board ofclaim 1, wherein the reinforced insulating layer comprises a through viaformed therethrough, and the first electrode pad and the secondelectrode pad are electrically connected to each other through thethrough via.
 4. A semiconductor package comprising: the wiring board ofclaim 1; and a semiconductor chip mounted on the wiring board.
 5. Thewiring board of claim 1, wherein the thickness of the reinforcedinsulating layer is 15 μm-100 μm.
 6. The wiring board of claim 1,wherein the thickness of the reinforced insulating layer is larger thanthe thickness of each of first and second insulating layers.
 7. Thewiring board of claim 1, wherein the reinforced insulating layer ishigher in mechanical strength that the first and second insulatinglayers.
 8. A method of manufacturing a wiring board, the methodcomprising: (a) providing a support member; (b) forming a firstmultilayer wiring structure on the support member, wherein the firstmultilayer wiring structure comprises: a plurality of first insulatinglayers each having a thickness of 15-35 μm; and a plurality of firstwiring layers, (c) forming a reinforced insulating layer containing (i)a reinforcing material including a woven cloth or a non-woven cloth and(ii) a resin material therein on the first multilayer wiring structure,the reinforcing material being impregnated by the resin material, thereinforced insulating layer having a thickness of 100 μm or less; (d)forming a second multilayer wiring structure on the reinforcedinsulating layer, wherein the second multilayer wiring structurecomprises: a plurality of second insulating layers each containing amaterial that consists of the same resin material as the reinforcedinsulating layer and does not include the reinforcing material, eachsecond insulating layer having a thickness of 15-35 μm; and a pluralityof second wiring layers, (e) removing the support member, wherein eachfirst insulating layer contains a material that consists of the sameresin material as the reinforced insulating layer and does not includethe reinforcing material.
 9. The method of claim 8, further comprising:(f) forming a solder resist layer on the second multilayer wiringstructure.
 10. The method of claim 8, further comprising: (g) forming athrough hole through the reinforced insulating layer; and (h) fillingthe through hole with a metal material to form a through via in thereinforced insulating layer.
 11. The method of claim 8, wherein thethickness of the reinforced insulating layer is 15 μm-100 μm.
 12. Themethod of claim 8, wherein the thickness of the reinforced insulatinglayer is larger than the thickness of each of first and secondinsulating layers.
 13. The method of claim 8, wherein the reinforcedinsulating layer is higher in mechanical strength that the first andsecond insulating layers.
 14. A method of manufacturing a semiconductorpackage, comprising; (a) providing a support member; (b) forming a firstmultilayer wiring structure on the support member, wherein the firstmultilayer wiring structure comprises: a plurality of first insulatinglayers each having a thickness of 15-35 μm; and a plurality of firstwiring layers, (c) forming a reinforced insulating layer containing (i)a reinforcing material and (ii) a resin material therein on the firstmultilayer wiring structure, the reinforcing material being impregnatedby the resin material, the reinforced insulating layer having athickness of 100 μm or less; (d) forming a second multilayer wiringstructure on the reinforced insulating layer, wherein the secondmultilayer wiring structure comprises: a plurality of second insulatinglayers each containing a material that consists of the same resinmaterial as the reinforced insulating layer and does not include thereinforcing material, each second insulating layer having a thickness of15-35 μm; and a plurality of second wiring layers, (e) removing thesupport member; and (f) mounting a semiconductor chip on the secondmultilayer wiring structure, wherein each first insulating layercontains a material that consists of the same resin material as thereinforced insulating layer and does not include the reinforcingmaterial.
 15. The method of claim 14, wherein the thickness of thereinforced insulating layer is 15 μm-100 μm.
 16. The method of claim 14,wherein the thickness of the reinforced insulating layer is larger thanthe thickness of each of first and second insulating layers.
 17. Themethod of claim 14, wherein the reinforced insulating layer is higher inmechanical strength that the first and second insulating layers.